Hydraulic valve device

ABSTRACT

The invention relates to a hydraulic valve device comprising a fluid connection arrangement ( 10 ) having different types of connections, and a mobile control device ( 18 ) for at least partially controlling connections of the fluid connection arrangement ( 10 ). As the control device ( 18 ) is provided with load reporting and load detecting connections ( 32,34; 36,38 ) that are interconnected and thereby associate a load reporting connection with a detection connection ( 32,38; 34,36 ), and, according to the displacement position of the control device ( 18 ), interconnect at least one part of the connections of the fluid connection arrangement ( 10 ) in a fluid-guiding manner, the control device can be brought with precision into the required functional positions, with a favourable dynamic driving behaviour.

The invention relates to a hydraulic valve device with a fluid connectorarrangement containing at least the following:

-   -   a pressure supply connector P    -   a return flow connector R    -   a section load sensing connector LS    -   two control connectors P_(A)′ and P_(B)′ and    -   two utility connectors A, B        and with a displaceable control means for at least partially        triggering connectors of the fluid connector arrangement.

DE 603 04 663 T2 discloses a hydraulic valve arrangement with a supplyconnector arrangement comprising a high pressure connector P and a lowpressure connector T, a working connector arrangement comprising twoworking or utility connectors A, B that can be connected to a consumer,a directional valve, and a compensation valve located between thedirectional valve and the supply connector arrangement P, T, whosepressure output is connected to the pressure input of the directionalvalve, the compensation valve having a relief output which can beconnected to the pressure output and a valve element in the form of aspool, which can be moved out of an initial position in oppositedirections, and which can be exposed to pressure on one side in the loadsensing line and to the force of a spring and, on the opposite side, canbe exposed to the pressure at the pressure output, the valve element,when moved in one direction, performing a pressure control function,and, when moved in the opposite direction, performing a pressure relieffunction, the spool having a longitudinal channel which is connected viaa transverse bore to the pressure output and ends in a first pressurechamber, and the longitudinal channel extending beyond the transversebore and being connectable via a closable opening to a second pressurechamber in which a relief pressure prevails.

With this known solution, it is possible to counteract so-calledparasitic pressure propagation, as can occur especially at higherpressures. When with the accompanying essentially inevitable leaks, thepressure propagates as far as an actuation motor which should not beactuated at all, but then sets it into motion, this can result in theunintended and hazardous raising of loads. In this connection, thesafety valves which have been used in the past can, however, likewise besubject to leaks and can even contribute to the formation of theparasitic pressure propagation.

EP 1 370 773 B1 discloses a comparable directional control valve as ahydraulic valve device which is used for controlling the pressure andthe flow of hydraulic oil from and to working connectors A, B of atleast one fluid consumer, in which the pressure and flow rate can becontrolled by means of a valve spool which can be moved in the spoolbore and which can be actuated by at least one drive, and by means ofannular channels dynamically connected thereto, at a so-called symmetrycenter point, on the axis of symmetry of the valve device there being atank connector annular channel as a so-called return flow connector andon both sides other annular channels being arranged likewisesymmetrically to the axis of symmetry. Due to the indicated symmetricalstructure, in the known solution it has a simple solution from amechanical viewpoint and thus allows economical fabrication. The knownvalve device intended to also have improved dynamic switching behaviorand a wide scope of operation.

The known solutions, however, overall are still complex in productionand for any fluidic application generally must be matched and designedaccordingly. The known solutions in the prior art with respect tooperating reliability still leave much to be desired.

Proceeding from this prior art, the object of the invention is thereforeto further improve them while maintaining their advantages such thatoperating reliability is still further improved and that the solutionaccording to the invention can be well executed relative to changingapplications in terms of a modular system. This object is achieved by ahydraulic valve device with the features of claim 1 in its entirety.

In that, as specified in the characterizing part of claim 1, the controlmeans is provided with load reporting and load sensing connectors which,interconnected in pairs, assign one load reporting connector to one loadsensing connector and which, depending on the position of movement ofthe control means, interconnect at least some of the connectors of thefluid connector arrangement to carry fluid, the control means as amodular block concept can be easily adapted to different fluidicapplications without greater modification or adaptation efforts to thehydraulic valve device thus becoming necessary. Due to the asymmetricalstructure of the control means, which acts in this respect on the fluidconnector arrangement, reliable triggering behavior is achieved and thecontrol means thus can be moved with an extremely favorable dynamicdisplacement behavior exactly into operating positions. The solutionaccording to the invention, viewed mechanically, is short, so that allrelevant switching and control positions for the hydraulic valve devicescan be implemented in a small installation space. In one especiallypreferred embodiment of the hydraulic valve device, according to theinvention, it is provided that the control means can also assume aso-called floating position without loss of resolution in the loweringand lifting region relative to the working or utility connectors A, B.Although, as shown, the proportional region is fully preserved inlifting and lowering, due to the special concept of the control means,the length of the housing still is kept short overall, to which theasymmetrical structural concept of the hydraulic valve device alsocontributes.

In another especially preferred embodiment of the solution according tothe invention, upstream from the control means a pressure compensator isconnected, with which so-called quantitative cutoff by load sensingpressure limitation in the spring chamber of the pressure compensator ispossible. In the solutions known in the prior art with a downstreampressure compensator, this function of quantitative cutoff is notpossible or can be obtained in a complex manner only by way ofcorresponding additional valve structures. In particular, the controlfunction of the pressure compensator is improved by a relatively largedrainage cross section discharging into the return flow connector. Theso-called floating position is also improved.

The hydraulic valve device according to the invention is detailed belowusing different exemplary embodiments. The FIGS. are schematic and notto scale.

FIGS. 1 and 2 show, as a longitudinal section, two exemplary embodimentsof the hydraulic valve device, the pressure compensator being located inits respective control position;

FIG. 3 shows, in the form of a circuit diagram, the design of the valvedevice as shown in FIGS. 1 and 2;

FIG. 4 shows, in a longitudinal section, a perspective view of thepressure compensator relating to the “floating position and quicktraverse” in the “quick traverse” position and with its differentconnection sites; and

FIG. 5 shows a simplified longitudinal section through an alteredembodiment of the valve spool with its various connection sites; in theupper half of the figure shown in the neutral position, in the lowerhalf of the figure in the deflected actuating position.

FIG. 1 shows a fluid connector arrangement designated as a whole as 10.This fluid connector arrangement 10 has a pressure supply connector P, areturn flow connector R, a section load sensing connector LS, twocontrol connectors P_(A)′, P_(B)′ and two utility connectors A, B. Theindicated fluid connectors LS, P_(A)′, R, P and P_(B)′, A and B areaccommodated in a control housing 12, viewed in the direction of lookingat FIG. 1, the lower end of the control housing 12 being provided with aconventional pressure compensator 14 that is connected upstream from theconnectors LS, P_(A)′, R, P and P_(B)′ and triggers them accordingly.With the pressure compensator 14 thus connected upstream, thequantitative cutoff function is attained by LS pressure limitation inthe spring chamber 16 of the pressure compensator, quantitative cutoffmaking sense, for example, when the steering cylinder, connected to theutility connectors A, B, is at the limit stop and the inflow amount isto be cut off to prevent overloads.

The control means 18 as such is triggered conventionally and thereforeis no longer detailed as conventional pilot valves 20, 22 which arereproduced in FIG. 3 with their hydraulic switching symbols and which,for the sake of simplicity, are shown in FIG. 1 only to the extent thattheir respectively assignable pilot housings 24, 26 are addressed. Onthe output side, the two pilot valves 20, 22 for the control means 18deliver two control pressures X_(A) and X_(B) which act in oppositedirections. Furthermore, a pump control pressure P_(ST) acts on therespective pilot valve 20, 22 and a tank connector line T₀ is likewiseconnected to the respective pilot valve.

The indicated control means 18 has a valve spool 28 which can be movedhorizontally, when viewed in the direction of looking at FIG. 1, andwhich in FIG. 1 is shown in its undeflected middle or neutral position.This neutral position of the valve spool 28, additionally, is supportedby two spring storage devices, which are made as compression springs 30and which are integrated in the respectively assignable spring chamberin the pilot housings 24, 26. This structure is conventional in thecorresponding hydraulic valve devices so that it will no longer bedetailed here. The control means 18 with the valve spools 28 is providedwith load reporting connectors 32, 34 and with load sensing connectors36, 38 which are interconnected in pairs to carry fluid. Specifically,the first load reporting connector 32 is connected to the second loadsensing connector 38 to carry fluid and the second load reportingconnector 34 is fluid-connected to the first load sensing connector 36.The indicated reporting connectors and sensing connectors are integratedin the valve spools 18 in the form of transverse radial bores and,depending on which axial position of movement the valve spool 18assumes, the indicated connectors 32, 34, 36 and 38 are connected to therespectively assignable connectors of the fluid connector arrangement 10to carry fluid or to block.

The type of possible switching positions follows from the conventionalswitching representation as shown in FIG. 3 so that this is no longerdetailed here. To produce the fluid-carrying connection between the loadreporting and load sensing connectors 32, 36; 34, 38 which can beassigned to one another in pairs, connecting channels 40, 42 locatedwithin the valve spool 28 are used. Here, one of the connecting channels40 is designed as a so-called middle channel which in the neutralposition of the control means 18 shown in FIG. 1 with its axial lengthcovers the region between the section load sensing connector LS and theutility connector B. In this respect, the middle channel, viewed in thedirection of looking at FIG. 1, is located on the left side of the valvespool 28 and runs in the form of an attached blind hole along thelongitudinal axis of the valve spool 28. In a parallel arrangementthereto another connecting channel 42 is at least one annularlongitudinal channel which in turn in the neutral position of thecontrol means 18 with its axial overall length covers at least theregion between the control connector P_(A)′ and the utility connector A.The load reporting and load sensing connectors 32, 36; 34, 38 are eachmade as radially running bores in the valve spool 28.

For producing the channel routing, the middle channel 40 is bordered byan insertion sleeve 44, which at least partially along its outsideperiphery, located in a definable middle region, with the inside wall ofthe valve spool 28 in this region borders the annular longitudinalchannel 42 which can also be formed here from a plurality of individualchannels (not shown) which are located concentrically to the middlechannel 40. The axial length of the insert sleeve 44 extends, as shownin FIG. 1, between a first load reporting connector 32 and a constrictedoffset site between the first load sensing connector 36 and the secondload sensing connector 38 at the height of the return flow connector R.While the insert sleeve 44 with its end which is the right end, viewedin the direction of looking at FIG. 1, is supported at the indicatedconstriction within the longitudinal bore of the valve spool 28, theopposite, other free end in the region of the first load reportingconnector 32 rests on a compression spring 45 which extends between asealing stopper 46 and the free end of the sleeve and keeps theinsertion sleeve 44 in its position with definable pretensioning.Longitudinal tolerances that may be present can be equalized in thesystem of the insertion sleeve 44 to the valve spool 28 by way of thisarrangement.

As FIG. 1 furthermore shows, the valve spool 28 along its outerperiphery has two control channels 48, 50 which are oriented lengthwiseand which in the neutral position of the control means 18 each dischargeinto the utility connector A and the utility connector B respectively.Accordingly, in the illustrated neutral position of the valve spool 28,the load sensing bore 36 emerges under the housing wall between theutility connector A and the return flow connector R.

Overall, the hydraulic valve device forms a so-called LS directionalcontrol valve with an upstream pressure compensator 14. As the switchingposition as illustrated in FIG. 3 shows, to protect parts of thehydraulic circuit, there is at least one pressure limitation valve 52,and the load sensing portion LS is adjusted relative to LS max by meansof a selector valve 54.

The hydraulic valve device according to the invention is made as a LSdirectional control valve with upstream pressure compensator 14 and hasa valve axis configuration which is short in terms of overall lengthwith few annular channels compared to known solutions. With the upstreampressure compensator 14 the already described function of quantitativecutoff by LS pressure limitation in the spring chamber of the pressurecompensator 14 is possible.

The embodiment as shown in FIG. 2 which is described below relates to aso-called floating position design, this valve structure beingcomparable to the valve structure as shown in FIG. 1. In this respect,in the solution as shown in FIG. 2, the same components are designatedwith the same reference numbers and the pertinent statements then alsoapply to the altered embodiment. The latter is described below only tothe extent it significantly differs mechanically from the abovedescribed embodiment as shown in FIG. 1.

In the embodiment as shown in FIG. 2, the valve spool 28 along its outerperiphery between the two groove-like control channels 48, 50,additionally, has separate pockets 56 which, separated from one anotherin different angle arrangements, extend along the indicated valve spool28. Furthermore, in the control channel 48, at least in the region ofthe utility connector A, a segmenting partition 48 is drawn in and inthe floating position shown in FIG. 2 the utility connector A is in afluid-carrying connection to the individual pockets 56 of the valvespool 28.

With the illustrated valve arrangement as shown in FIG. 2, usingadditional pockets 56 between the two control channels 48, 50, afloating position for the valve can be achieved without loss ofresolution in the lowering and lifting region of the hydraulicarrangement.

With the valve device solution according to the invention, it ispossible to achieve the combination of a floating position and a quicktraverse in a mobile valve in a spool construction; this is especiallyefficient for use in conventional machinery (not shown) in whichmachines must be quickly moved and/or when they must be picked up andput down in the manner of a pivoting position; this is for example thecase for a reciprocating finger bar mover of a slope mower or the like.

FIG. 4, which shows only the valve spool 28 together with the housingconnectors LS, P_(A)′, A, R, B, P_(B)′ also contributes to theimplementation of the pertinent quick traverse position. In the quicktraverse position, the fluid-carrying connection P to B is maintained,the connection A to R being closed and, for this purpose, the connectionA to P being opened in order to enable return flow from the rod side(annular surface) of a working cylinder of the machinery which is notdetailed toward the ground side (bar mower application). One loadsensing bore of the valve spool 28 is in the pressure connector B andone load reporting bore is routed to an assignable housing pocket in thevalve spool 28. This load reporting bore ends on the jacket surface ofthe valve spool 28, the jacket surface being locally routed around theexit of the reporting bore. Otherwise here the jacket surface is openedand recessed in order to form a return flow cross section from A to P.So that the rotary position of the load reporting bore and housingpocket is preserved, there is a mechanical locking element which is notshown for the valve spool 28. The other load sensing bore is then in theR-channel and the corresponding other load reporting bore is under thehousing wall between P_(A)′ and the A-channel. The quick traverseposition of the valve spool 28 is reached by overtravel via theso-called lifting position and the floating position via the so-calledlowering position of the connected hydraulic components of the machine.This corresponds to the desired operating states on the indicatedmachines since the quick traverse as a switching position should not beengaged directly from “neutral” in order to avoid an overly strongswitching pressure.

Since the reporting channel of the load sensing pressure must be openedinto the spring chamber of the section pressure compensator over theentire stroke of the valve spool 28, the valve axis cannot be shortenedrelative to this function; this would benefit the overall size of thevalve device. Conversely, an improvement can be achieved in the coveringof the reporting bore on the valve spool 28. For the proposal accordingto the invention as shown in FIGS. 1 and 2, the LS reporting borestravel into the pressure channels, insofar as the floating position isaddressed there. In order to avoid a malfunction in the form of animpermissible flow from other pressure channels into the LS reportingcircuit, additional means are used in the form of check valves 60, asshown in FIG. 5.

In the neutral position of the valve spool 28 (shown in the upper halfof the figure), the radial load sensing bore and the radial loadreporting bore are each covered by the housing wall. The concept of ashort construction dictates that in the “lifting” position (workingposition of the machinery) the load reporting bore of the connector Aruns into the P connector and the load sensing bore into the Rconnector. To prevent short-circuiting from P to R a check valve 60 isinstalled in the corresponding connecting line 62. In the so-calledlowering position and in the neutral position, a spring then holds thecheck valve 60 open so that here both pressure reporting, as well asdynamic flow which is dictated by the control movements of the connectedpressure compensator 14, are ensured.

The pressure drop on the check valve for rapid control movements of thepressure compensator 14 and the spring force are matched to one anothersuch that for rapid control movements as correspond to a high flow rate,the check valve 60 cannot close. In the lifting position, however, theleakage flow rate from P to R immediately becomes high enough for thepressure drop over the open check valve 60 to overcome the spring forceand the check valve reliably closes. In this respect, therefore, thefloating position is also reached by overtravel via the loweringposition and the lifting position of the respectively connected machine.Here, it is possible that only when the machine has been placed, forexample, on the ground in the lowered position is the floating positionthen engaged.

In the embodiment as shown in FIGS. 1 and 2, the check valves 60 shownin FIG. 5 can also be inserted into the control channels 48, 50 there(not shown), and then the closing ball opens in the direction of theload sensing connector in order to achieve comparable results, asdescribed above.

With the valve device according to the invention, standard directionalcontrol valves with the three basic positions for neutral, lifting, andlowering can be expanded within the scope of operation to a floatingposition and/or a quick traverse position without the spool stroke beinglengthened in doing so, as in the known spool valve solutions, in orderto travel into the additional position with the desired logicoperations; rather, with the solution according to the invention, thisspool lengthening can be entirely avoided or the spool valve axis can beshortened.

1. A hydraulic valve device with a fluid connector arrangement (10)comprising at least the following: a pressure supply connector P, areturn flow connector R, a section load sensing connector LS, twocontrol connectors (P_(A)′) and (P_(B)′), and two utility connectors A,B and with a displaceable control means (18) for at least partiallytriggering individual connectors of the fluid connector arrangement(10), characterized in that the control means (18) is provided with loadreporting and load sensing connectors (32, 34; 36, 38) which,interconnected in pairs, assign one load reporting connector to onesensing connector (32, 34; 36, 38) and which, depending on the positionof movement of the control means (18), interconnect at least some of theconnectors of the fluid connector arrangement (10) to carry fluid. 2.The valve device according to claim 1, characterized in that the controlmeans (18) has a valve spool (28) with fluid-carrying connectingchannels (40, 42) which interconnect the load reporting and load sensingconnectors (32, 34; 36, 38) which can be assigned to one another inpairs.
 3. The valve device according to claim 2, characterized in thatone of the connecting channels (40) is made as a so-called middlechannel which, in the neutral position of the control means (18), withits axial length covers the region between the section load sensingconnector (LS) and the utility connector (B).
 4. The valve deviceaccording to claim 2, characterized in that at least one other of theconnecting channels (42) is made as a longitudinal annular channelwhich, in the neutral position of the control means (18), with its axiallength covers at least the region between the control connector (P_(A)′)and the utility connector (A).
 5. The valve device according to claim 4,characterized in that the middle channel (40) is bordered by aninsertion sleeve (44) which limits the respective longitudinal annularchannel (42) along its outside periphery with the inside wall of thecontrol means (18).
 6. The valve device according to claim 1,characterized in that the control means (18) can be triggered by twopilot valves (20, 22) which act in opposite directions, and is heldspring-centered in its neutral position.
 7. The valve device accordingto claim 2, characterized in that the valve spool (28) along its outerperiphery has at least two groove-like control channels (48, 50) whichare oriented lengthwise and which, in the neutral position of thecontrol means (18), discharge into the utility connector (A) and theutility connector (B), respectively.
 8. The valve device according toclaim 7, characterized in that in the neutral position of the valvespool (28), one radial load sensing bore (36, 38) at a time offset onthe periphery to the assignable control channel (48, 50) ends under thathousing partition which is situated between the utility connectors (A,B) and the return flow connector (R).
 9. The valve device according toclaim 1, characterized in that the load sensing bores (36, 38) areseparated fluid-tight from one another.
 10. The valve device accordingto claim 2, characterized in that in the neutral position of the valvespool (28), the radial load reporting bores (32, 34) each discharge onboth sides next to the section load sensing connector (LS) and arecovered by the housing wall.
 11. The valve device according to claim 7,characterized in that on the neutral position of the valve spool (28), alongitudinal channel in the valve spool (28) connects the section loadsensing connector (LS) to the trigger space (X_(A)) of the device tocarry fluid.
 12. The valve device according to claim 1, characterized inthat the pressure compensator (14) which also at least partiallytriggers the fluid connector arrangement (10) is connected upstream tothe control means (18) with its fluid connectors.
 13. The valve deviceaccording to claim 8, characterized in that in the floating position ofthe valve spool (28), one of its annular channels (48), which dischargesinto the utility connector (A), contains a partition (58) that separatesthe control connector (P_(A)′) from the utility connector (A).
 14. Thevalve device according to claim 1, characterized in that at least forsome of the connecting channels (40, 42) between the load reporting andload sensing connectors, which can be assigned to one another in pairs,at least one check valve (60) is inserted.
 15. The valve deviceaccording to claim 14, characterized in that the respective check valve(60) within the connecting channels closes in the direction of loadsensing A and load reporting B or load sensing B and load reporting A.16. The valve device according to claim 14, characterized in that thevalve spool (28) can be displaced beyond a maximum working position intoa quick traverse position.
 17. The valve device according to claim 14,characterized in that the valve spool (28) in its quick traverseposition connects the control connector (P_(B)′) to the utilityconnector (B) by means of a control groove (50) and by its additionalpocket-like connecting channels between the reporting bores (LS_(A))connects the utility connector (A) and the control connector (P_(A)).18. The valve device according to claim 14, characterized in that theload reporting bores (LS_(A)) and (LS_(B)) of the valve spool (28) arealigned in their rotary position to the local widenings of the sectionload sensing connector (LS).